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x86/boot: Warn on future overlapping memcpy() use

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If an overlapping memcpy() is ever attempted, we should at least report
it, in case it might lead to problems, so it could be changed to a
memmove() call instead.

Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Baoquan He <bhe@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Lasse Collin <lasse.collin@tukaani.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/1462229461-3370-3-git-send-email-keescook@chromium.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Kees Cook 2016-05-02 15:51:01 -07:00 committed by Ingo Molnar
parent dc425a6e14
commit 00ec2c3703
1 changed files with 13 additions and 3 deletions
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16
arch/x86/boot/compressed/string.c
View file

@ -10,7 +10,7 @@
#include "../string.c"
#ifdef CONFIG_X86_32
void *memcpy(void *dest, const void *src, size_t n)
static void *__memcpy(void *dest, const void *src, size_t n)
{
int d0, d1, d2;
asm volatile(
@ -24,7 +24,7 @@ void *memcpy(void *dest, const void *src, size_t n)
return dest;
}
#else
void *memcpy(void *dest, const void *src, size_t n)
static void *__memcpy(void *dest, const void *src, size_t n)
{
long d0, d1, d2;
asm volatile(
@ -55,10 +55,20 @@ void *memmove(void *dest, const void *src, size_t n)
const unsigned char *s = src;
if (d <= s || d - s >= n)
return memcpy(dest, src, n);
return __memcpy(dest, src, n);
while (n-- > 0)
d[n] = s[n];
return dest;
}
/* Detect and warn about potential overlaps, but handle them with memmove. */
void *memcpy(void *dest, const void *src, size_t n)
{
if (dest > src && dest - src < n) {
warn("Avoiding potentially unsafe overlapping memcpy()!");
return memmove(dest, src, n);
}
return __memcpy(dest, src, n);
}